Winds from black holes can influence the evolution of nearby galaxies

Clouds of gas in a distant galaxy are being pushed ever faster—at more than 10,000 miles per second—between neighboring stars by bursts of radiation from the supermassive black hole at the center of the galaxy. It’s a discovery that helps shed light on how active black holes can continuously shape their galaxies by encouraging or suppressing the development of new stars.

A team of researchers led by University of Wisconsin-Madison astronomy professor Catherine Grier and recent graduate student Robert Wheatley detected the accelerating gas using years of data from a quasar, a particularly bright and turbulent type of black hole billions of light-years away. the constellation Boötes. They presented their findings today at the 244th meeting of the American Astronomical Society in Madison.

Scientists believe that black holes are located at the center of most galaxies. Quasars are supermassive black holes surrounded by disks of matter that are pulled in by the enormous gravitational force of the black hole.

“The material in this disk is always falling into the black hole, and the friction of that thrust and thrust heats the disk and makes it very, very hot and very, very bright,” says Grier. “These quasars are really luminous, and because there is a large temperature range from the interior to the far reaches of the disk, their emission covers almost the entire electromagnetic spectrum.”

The bright light makes quasars nearly as old as the universe (up to 13 billion light-years away) visible, and the wide range of their radiation makes them particularly useful for astronomers to study the early universe.

The researchers used more than eight years of observations of the quasar, called SBS 1408+544, collected by the Sloan Digital Sky Survey program now known as the Black Hole Mapper Reverberation Mapping Project. They tracked winds composed of gaseous carbon by picking up light from the quasar that was missing — light that was absorbed by the gas. But instead of being absorbed at exactly the right spot in the spectrum to indicate carbon, the shadow moved further from home with each new look at SBS 1408+544.

“This shift tells us that the gas is moving fast and getting faster,” says Wheatley. “The wind accelerates because it is pushed by radiation that is reflected from the accretion disk.”

Scientists, including Grier, have suggested that they have previously observed accelerating winds from the accretion disks of black holes, but this has yet to be backed up by data from more than a few observations. The new results come from around 130 observations of SBS 1408+544 made over nearly a decade, allowing the team to reliably identify the speed increase with high confidence.

Winds pushing gas out of a quasar are of interest to astronomers because they represent a way in which supermassive black holes can influence the evolution of the galaxies that surround them.

“If they are energetic enough, the winds can travel all the way to the host galaxy where they could have a significant impact,” says Wheatley.

Depending on the circumstances, the quasar’s wind could provide pressure that squeezes the gas together and accelerates the birth of a star in its host galaxy. Or it could siphon off fuel and prevent a potential star from forming.

“Supermassive black holes are big, but they’re really small compared to their galaxies,” says Grier. “That doesn’t mean they can’t ‘talk’ to each other, and it’s the way they talk to each other that we’ll have to take into account when we model the effects of these kinds of black holes.”

The SBS 1408+544 study, published today in The Astrophysical Journal they included collaborators from York University, Pennsylvania State University, the University of Arizona, and others.